Clay Questions

Which clay body fires to the highest possible cone for the longest
amount of time and what temperature would that be?

Where could I buy this clay? Name Brands???

Does putting a glaze on the material make it physically stronger....or
not....? More resistant to temperature extremes....or not.....?

Does the stoneware become weaker by firing it more than once?

Thank you in advance for your help.
Mary

"Mary" wrote in message
om...
Which clay body fires to the highest possible cone for the longest
amount of time and what temperature would that be?

Cone 12 is the highest cone, at 2471degrees F at a heating rate of 540
degree rise per hour.
I do not know of anyone firing to this temperature. Usually around cone 10
(2426degrees F at a heating rate of 540 degrees per hour)
Some industrial ceramic compounds are fired to even greater temperatures,
but you will not have access
to the equipment needed to reach those temperatures.
You're going to have a bit of luck just
getting to cone 11 or 12 with a standard kiln!
Please remember that "cone" refers to not only temperature,
but heat work as well. How long it's fired, at what degree rise
how long it soaked at a given temp, etc. You would be better
off using the word "temperature" for your inquiry above.

Where could I buy this clay? Name Brands???

Go online, go to http://www.google.com and do a search for
"clay or pottery suppliers"
then find the one closest to you.
Look in their (online or paper) catalog for their high fire clays.
It does no good to find
a highfire clay from a supplier that is a gazillion miles away.
The shipping costs will eat you alive.

Does putting a glaze on the material make it physically stronger....or
not....?

Yes, and it can be water resistant too, depending on the application.

More resistant to temperature extremes....or not.....?

No. Except in rare cases. It really depends on the formula of the
clay body and the formula of the glaze.

Does the stoneware become weaker by firing it more than once?

Generally no, unless you repeatedly fire to a temperature it was not meant
for ( too high) or
underfire it (and it fails to mature). Bear in mind that the word
"stoneware" applies
to at least 3450 (maybe more) different types of clay, all different
formulations and materials. Pick one.
But most clay bodies generally follow the rule above.

Thank you in advance for your help.
Mary